To effect timely and safe operation of online testing routines within field devices, such as valves, used in a process control system or a safety system.

Using one or more testing blocks which are easy to implement and to place in the process control system or safety system, enable the periodic or on-demand testing of field devices to be integrated into the normal and on-going operation of the process control system or safety system without causing scheduling or connection problems and without the need to rely on maintenance or other personnel, thereby providing better monitoring of the operational status of the field devices.